Megadolichobasilar (MDB) is a rare arterial anomaly consisting of excessive elongation, widening and tortuosity of the basilar artery. It may be associated with different neurological disturbances, including cerebral ischemic stroke, compression of the cranial nerves, hydrocephalus, headache and vertigo. Ulcerative colitis (UC) is an inflammatory bowel disease of unknown aetiology which may be complicated by arterial or venous cerebral illness, among others neurological anomalies. We report a patient suffering from UC who presented ischemic stroke. The neurorradiological studies showed incompletely thrombosed MDB accompanied by a distal aneurysm from narrow zone. These findings advised anticoagulant treatment which leads to neurological stability. To our knowledge, it is the first report of MDB associated with UC. Although this association is probably fortuitous, we discuss both the etiopatogeny and the possibly influence of each one on the clinical picture.